Reflector plate

ABSTRACT

A reflector plate of transparent thermoplastic material having a planar surface designed to face the reflecting light source and a second surface having triple reflectors uniformly distributed and closely juxtaposed with the surface having the triple reflectors, characterized by the presence of a plurality of feet projecting above the tips of the triple reflectors.

United States Patent Langenbach Sept. 16, 1975 [54] REFLECTOR PLATE 3,359,671 12/1967 Nier et al 350/103 3,417,959 12 1968 Sch 1112 350 102 [75] Inventor: Erwin Langenbach, Buchholz, u

Germany [73] Assignee: Erwinsick Optik-elektronik, Primary Examiner-Alfred E. Smith Waldkirch, Germany Assistant Examiner-Michae1 J. Tokar 22 Filed: Jan. 10, 1974 [21] Appl. No.: 432,189

[57] ABSTRACT [30] Foreign Application Priority Data Jan. 15, 1973 Germany 2301868 A reflector plate of transparent thermoplastic material having a planar surface designed to face the reflecting 52 US. Cl. 350/103; 350/106; 404/9 light Source and a Second Surface having triple reflee- 51 Im. cl. G02B 5/12 tors uniformly distributed and cleeely juxtaposed with 58 Field of Search 350/97 103, the Surface having the triple reflectors, characterized 3 50/106; 404/9 16 by the presence of a plurality of feet projecting above the tips of the triple reflectors. [56] References Cited UNITED STATES PATENTS 4/1936 Egnon 350/106 21 Claims, 6 Drawing Figures PATENTED BSQSTB SET 2 BF 3 REFLECTOR PLATE L The invention relates to a reflector plate of thermoplastic material, whose one surface is planar and whose other surface has triple reflectors uniformly distributed and closely juxtaposed according'to a regular pattern. The triple reflectors comprise cubes whose one angle projects upwards from the plane of the plate. 7

As is known such reflector plates have the property within a certain space angle of reflecting back into themselves light inciding on the planar, side independent of its direction of incidence. Such reflector plates are used, e.g. in accident prevention light curtains.

In the manufacture of reflector plates from thermoplastic material a uniform surface quality of each individual triple reflector is only obtained if edges or margins are provided beyond the overall effective triple surface during the extrusion process. These edges can have any shape and serve for stabilisation and support purposes. I

If a reflector plate comprising several partial plates is i to be assembled into an uninterrupted, large reflecting surface area the, material of the edges not provided with a triple pattern must first be cut away. The partial plates with the side carrying the pattern must now be placed against a fixed support plate e.g. an aluminium sheet, whilst from the opposite, optically effective side a glass plate is applied. The overall arrangement of support plate, partial plates and glass plate is fixed, in a housing. However, the sensitive tips of the individual triple reflectors can then be damaged e.g. by vibrations, which can greatly impair the optical efficiency of the reflector plate.

The problem of. the invention is therefore toso further develop a reflector plate of the type described hereinbefore that even after cutting away the edges and placing the tips of the reflector plate on a base there is no danger of damaging or impairing the sensitive triple reflector plates. v

According to the invention this problem is solved in that at several spaced points of the triple pattern feet projecting over the tips of the triple pattern are arranged over at least part of the triple reflector. Prefera: bly they are located where due to the triple positioning there would in any case be dead zones. it is surprising that inspite of this interruption of the triple pattern at the points defined by the invention the optical quality of the reflector plate is in fact improved rather than impaired because damage to the sensitivetriple tips is effectively prevented.

The feet are preferably provided pattern and are uniformly spaced.

Advantageously the feet are located on those sides where smooth edges projecting over the triple area are provided which on assembling the reflectorplates to form larger units can be cut away in the intersection areas.

It is very advantageous from a manufacturing standat the sides of. the

point if the feet are also extruded during manufacture According to a preferred embodiment the triple reflectors which are hexagonal inplan view with .two facing sides run parallel to the sides of theoverall pattern. The sides of the overall pattern preferably coincide alternately with one hexagonal side of a triple reflector and the central axis of the next triplereflector.

Another embodiment is constructed sothat the feet have the cross-section of anequilateral triangle and in each case are located on the pattern sides in one of the triangular areas. Thus, only one sixth of each hexagonal surface zone is required for each foot.

The ends of the feet are preferably flat so as to provide a good support surface Advantageously the feet project more than 0.5 mm but less than i mm above the tips According to a first particularly preferred embodiment the reflector plate according to the invention comprises hexagonal partial plates, whereby the edges thereof run along the sides of the hexagonal triple reflector and the feet are provided solely in the hexagons bisected by. the cut. This construction has the advantage that the cut-triple reflectors, which are in any case not effective from an optical standpoint are provided for receiving the feet. Thus, without impairing the reflecting properties of the reflector plate assembled from partial plates an improved mechanical construction is achieved which ensures a long life of the reflector plate'even in rough practical operation According to a further advantageous embodiment the reflector plate according to the invention comprises rectangular partial plates, whereby one edge of the partial plate runs along the sides of the hexagonal triple reflector and the other rectangular edge runs along the tips of the hexagons. The feet are only provided in the bisected hexagons on the first edge. In this embodiment the feet are once again located in the dead zones which i in any case occur at the intersections Advantageously in section the triplereflectors have a sawtoothed shape along the first edge. According to the invention the feet are located on the short flanks of the sawteeth.

Advantageously the flat isosceles triangles remaining onthe second edge are cut out. if they are cut out with the optically'necessary precision the partial plates can be fitted into one another at the sawn intersections, so that the dead zones are there reduced to a minimum. At the same time the perfect mounting of the part plates on the other edges by the feet is ensured.

Preferably the part plates with the feet are mounted on a common support plate. From the opposite side a glass plate is appropriately placed against the part plates and the overall arrangement is secured in place.

A slip-proof, vibration-proof and very stable mounting is obtained if the aluminium support plate rests in a housing on a rubber buffer.

Accordingto an advantageous embodiment all the partial plates are arranged level with a step which passes completely round the housing which is covered with a sha'pable casting compound up to the outer edge of the partial plates. Appropriately the casting compound protrudes slightly above the planar surface of the partial plates and therefore also rests sealingly against the glass plate.

Other and further objects of the present invention will be apparent from the following description and claims and are illustrated in the accompanying drawings which, by way of illustratiomshow preferred embodiments of the present invention and the principles thereof and what are now considered to be the best modes contemplated for applying these principles. Other embodiments of the invention embodying the same or equivalent principles may be used and structural changes may be made as desired by those skilled in the art without departing from the present invention and the scope of the appended claims. I

FIG. 1 a plan view of a reflector plate according to v the invention FIG. 2 a section along side 13 in FIG. 1"

FIG. 3 a plan view of a reflector plate according to the invention comprising a plurality ,of hexagonal partial plates a FIG. 4 a section along line IV IV of FIG. 3 FIG. '5 a plan view of a reflector plate according to the invention comprising rectangular partial plates FIG. 6 a section along line'VI VI of FIG. 5.

According to FIGS. 1 and 2 a rectangular partial reflector plate 19 whilst leaving two edges 16 and 17 is provided with a regular pattern of triple reflectors ll extruded on the plate made from thermoplastic material. In plan view the triple reflectors 11 are hexagonal and aligned and arranged inthe manner shown in FIG. 1 relative to sides l2, 13 or edges 16, 17.

The feet l5,having a planar. surface according to the invention are extruded in a uniformly spaced manner on the edges. Feet 15 project somewhat further from theplate then the tips 14 of the triple reflectors 11. It is essential that in the manner indicated in detail vin FIG. 1 the feet are in each case arranged within a bisected hexagonal triple reflector on one of the edges l2, 13. The optical function of the reflector plate is in noway impaired and at the same time a support surface for the reflector plate is provided which effectively prevents the sensitive tips being damaged or impaired.

FIGS. and 6 show how a partialreflector plate 19 according to FIGS. land 2 can be combined with similar partial plates to form a larger reflector plate. It is assumed that the beam of light scanning the reflector plate performs a scanning movement according to the double arrow f. According to the invention the individual partial plates 19 are so arranged relative to scanning direction f that the edges carrying feet pointin thescanning direction. Perpendicular to the edges l2 l3 carrying feet 15 thev reflector plate is cut in such a way that thetwo other edges run along the tips of the hexagons, whereby isosceles triangles 20 are lefttbehind which are juxtaposed in the manner shown in FIG. 5. Triangles 20 can also be cut out, whereby the dead zone in the particular intersection area is greatly reduced in size or even completely eliminated.

Partial plates 19 cut so as to give a desiredreflector plate size are then according to FIG. 6 placed on an aluminium support plate 21 common to all the partial plates and which via a round rubber member 24 rests on the base of a housing 23. The arrangement is such that the feet 15 rest on the aluminium plate21, whereas the tips of the triple reflector 12 are at a reasonable distance therefrom. I

Theplanar surfaces of partial plates 19 facing the triple tips are covered by a glass plate 22 common to all the partial plates.

Around and within the housing extends a step 26 which surrounds the outer edges of partial plates 19 and is cast with a silicone casting compound to reliably prevent entry of moisture or dirtinto the housing. The casting compound protrudes slightly above the planar surface of the partial plates 19 so that glass plate 22 which projects on all sides over partial plates 19 rests sealingly against'casting compound This prevents moistureand dirt from penetrating between partial plates 19 and glass plate 22.

The complete arrangement of support plate 21, partial plates 19 and glass plate 22 is compressed by v clamping members 27 fixed to housing 23 by means of screws. The connection can also be provided by sheet steel springs bent into a U-shape instead of screws.

i In the embodiments according to FIGS/3 and 4,

where the same reference numerals indicate the same members as in FIGS. 5 and 6,the reflector plate according to the invention comprises hexagonal partial plates 18. The hexagons are completely symmetrical and are out along the sides of the triple hexagons. According to the invention the feet l5 areprovided in the bisected hexagons on the edge where they have no disadvantageous optical effect and can perform their mechanical function completely satisfactorily. With reference to the scanning direction F the hexagons are aligned in theinventive manner according to FIG. 3.

To arrive at an overall arrangement according to FIG. 3 the hexagons are bisected at the edges as shown in FIG. 3, so that the feet provided at the edges of the hexagons can also satisfactorily hold in place the cut side plates. i

While there has been described and illustrated the preferred embodiments of the invention, it is to be understood thatthese are capable of variation and modification, and it is therefore not desired to be limited to the precise details set forth, but to include such modifications and alterations as fall within the scope of the appended claims. 1

What is claimed is:

'1. Reflector plate of thermoplastic transparent material whose surface facing .the reflecting light is planar and whose other surface has triple reflectors uniformly distributed and closely juxtaposed according to.a regular pattern wherein the improvement comprises providing in at least part of the triple reflectors a plurality of feet arranged at spaced points of the triple pattern and projecting above the tips of the triple reflector thereof.

2. Reflector plate as claimed in claim 1, wherein the feet are provided on the sides of the pattern.

3. Reflector plate as claimed in claim 2, wherein the feet are arranged with a uniform spacing on the sides of the pattern.

4. Reflector plate as cl'aim'ed in claim 1 wherein the feet are provided on the sides where there are smooth edges protruding above the triple area. 1 1

5. Reflector plate as claimed in claim I, wherein the feet are also extruded during manufacture.

6. Reflector plate as claimed in claim 1, wherein the in plan view hexagonal triple reflectors with two facing sides are located parallel to the sides of the overall pattern. t

7. Reflector plate as claimed in claim 6, wherein the sides of the overall pattern coincide alternately with one hexagonal side of one triple reflector and the central axis of the next triple reflector. t

8. Reflector plate as claimed in claim 7, wherein the feet have the cross-section of an equilateral triangle being located in each case in one of the triangular zones on the pattern sides.

9.Reflector plate as claimed in claim 1, wherein the ends of the feet are flat.

l0. Reflector plate as claimed in claim 1, wherein the feet protrude more than 0.5 'rnm above the tips.

11. Reflector plate as claimed in claim 1, wherein it comprises hexagonal partial plates, whereby the edges of the partial plates run along the sides of the hexagonal triple reflector and the feet are provided exclusively in the bisected hexagon formed by the cut.

l2. Reflector plate as claimed in claim 1, wherein it comprises rectangular partial plates, whereby one edge of the partial plates runs along the sides of the hexago' nal triple reflectors and the other which is at right angles thereto runs along the tips of the hexagons and the feet are provided only in the bisected hexagons present on the first edge.

13. Reflector plate as claimed in claim 12, wherein in section the triple reflectors have a sawtooth shape along the first edge.

14. Reflector plate as claimed in claim 12, wherein the flat isosceles triangles remaining at the second edge are cut out.

15. Reflector plate as claimed in 12, wherein the partial plates and the feet are mounted on a common support plate.

16. Reflector plate as claimed in claim 15, wherein from the opposite side a glass plate is placed against the partial plates and the overall arrangement is secured in place.

17. Reflector plate as claimed in claim 16, wherein the aluminium support plate is placed in a housing on a rubber buffer.

18. Reflector plate as claimed in claim 16, wherein all the partial plates are positioned level with a step which passes round the inside of the housing and which is covered by a shapable casting compound up to the outer edge of the partial plates.

l9. Reflector plate as claimed in claim 18, wherein the casting compound projects slightly above the planar surface of the partial plates and therefore rests tightly against the glass plate.

20. Hexagonal partial reflector plate of thermoplastic transparent material whose surface facing the reflecting light is planar and whose other surface has hexagonal triple reflectors uniformly distributed and closely juxtaposed according to a regular pattern wherein the improvement comprises cutting the edges of the partial plate along the side of the hexagonal triple reflector, said improvement further comprising a plurality of feet spaced exclusively in the bisected hexagon formed by the cut.

21. Rectangular partial plate of thermoplastic transparent material whose surface facing the reflecting light is planar and whose other surface has hexagonal triple reflectors uniformly distributed and closely juxtaposed according to a regular pattern wherein the improvement comprises having a first edge of the partial plate running along the side of the hexagonal triple reflector, and the other edge, which is at right angles thereto, running along a tip of the hexagon, said improvement further comprising a plurality of feet spaced exclusively in the bisected hexagon and present on said first edge. 

1. Reflector plate of thermoplastic transparent material whose surface facing the reflecting light is planar and whose other surface has triple reflectors uniformly distributed and closely juxtaposed according to a regular pattern wherein the improvement comprises providing in at least part of the triple reflectors a plurality of feet arranged at spaced points of the triple pattern and projecting above the tips of the triple reflector thereof.
 2. Reflector plate as claimed in claim 1, wherein the feet are provided on the sides of the pattern.
 3. Reflector plate as claimed in claim 2, wherein the feet are arranged with a uniform spacing on the sides of the pattern.
 4. Reflector plate as claimed in claim 1, wherein the feet are provided on the sides where there are smooth edges protruding above the triple area.
 5. Reflector plate as claimed in claim 1, wherein the feet are also extruded during manufacture.
 6. Reflector plate as claimed in claim 1, wherein the in plan view hexagonal triple reflectors with two facing sides are located parallel to the sides of the overall pattern.
 7. Reflector plate as claimed in claim 6, wherein the sides of the overall pattern coincide alternately with one hexagonal side of one triple reflector and the central axis of the next triple reflector.
 8. Reflector plate as claimed in claim 7, wherein the feet have the cross-section of an equilateral triangle being located in each case in one of the triangular zones on the pattern sides.
 9. Reflector plate as claimed in claim 1, wherein the ends of the feet are flat.
 10. Reflector plate as claimed in claim 1, wherein the feet protrude more than 0.5 mm above the tips.
 11. Reflector plate as claimed in claim 1, wherein it comprises hexagonal partial plates, whereby the edges of the partial plates run along the sides of the hexagonal triple reflector and the feet are provided exclusively in the bisected hexagon formed by the cut.
 12. Reflector plate as claimed in claim 1, wherein it comprises rectangular partial plates, whereby one edge of the partial plates runs along the sides of the hexagonal triple reflectors and the other which is at right angles thereto runs along the tips of the hexagons and the feet are provided only in the bisected hexagons present on the first edge.
 13. Reflector plate as claimed in claim 12, wherein in section the triple reflectors have a sawtooth shape along the first edge.
 14. Reflector plate as claimed in claim 12, wherein the flat isosceles triangles remaining at the second edge are cut out.
 15. Reflector plate as claimed in 12, wherein the partial plates and the feet are mounted on a common support plate.
 16. Reflector plate as claimed in claim 15, wherein from the opposite side a glass plate is placed against the partial plates and the overall arrangement is secured in place.
 17. Reflector plate as claimed in claim 16, wherein the aluminium support plate is placed in a housing on a rubber buffer.
 18. Reflector plate as claimed in claim 16, wherein all the partial plates are positioned level with a step which passes round the inside of the housing and which is covered by a shapable casting compound up to the outer edge of the partial plates.
 19. Reflector plate as claimed in claim 18, wherein the casting compound projects slightly above the planar surface of the partial plates and therefore rests tightly against the glass plate. Pg,16
 20. Hexagonal partial reflector plate of thermoplastic transparent material whose surface facing the reflecting light is planar and whose other surface has hexagonal triple reflectors uniformly distributed and closely juxtaposed according to a regular pattern wherein the improvement comprises cutting the edges of the partial plate along the side of the hexagonal triple reflector, said improvement further comprising a plurality of feet spaced exclusively in the bisected hexagon formed by the cut.
 21. Rectangular partial plate of thermoplastic transparent material whose surface facing the reflecting light is planar and whose other surface has hexagonal triple reflectors uniformly distributed and closely juxtaposed according to a regular pattern wherein the improvement comprises having a first edge of the partial plate running along the side of the hexagonal triple reflector, and the other edge, which is at right angles thereto, running along a tip of the hexagon, said improvement further comprising a plurality of feet spaced exclusively in the bisected hexagon and present on said first edge. 